4.3L fuel pressure problem

[caveeagle]

In my 2000 4.3L v6: cold starts and runs just fine. Fuel pressure at idle is at 54lbs. This is a little lower than the shop manual (60-66lbs) but this could just be my el-cheapo fuel guage reading low.

Once the engine warms up..... It will not restart. Ignition spark seems to be ok. In the 'non-starting' mode, I am only getting around 40lbs of pressure and I also don't get the initial 'jolt' of higher fuel pressure when the key is turned to 'on'.

Fuel pump relay was just changed and that did not have any impact on the problem. The fuel pump was replaced with a new carter pump back in Jan07. It has been running fine all year untill 2 weeks ago.

Any suggestions on what could be causing this problem? It seems to only effect the starting mode when engine is hot??

[caveeagle]

Wow! 32 views and no suggestions.....

At least I feel a little better about being stumped by this one....

[91parkave]

check for a vacum lueak, then make sure your vac tube running to the fuel pressure regulator is in good condition, after that, id suspect the FPR to be replaced next..

[caveeagle]

Thanks!

I will check that out this morning.

[antixx]

i have the 2.8 and have low fuel pressure but i also have low vaccuum pressure and i found a faulty egr valve, fixed my vaccuum problem! dont know if that will help but it did for me

[caveeagle]

I need to get a vacum guage. But that is a good idea for me to check.

Thanks.

[caveeagle]

Someone suggested to me the following:

the low oil pressure sender could be cutting our the fuel pressure during start-up. Because oil pressure is typically lower when the engine is hot.

Any ideas on how to check this? Can I bypass the OP sender?

[caveeagle]

Well, I think I finally have this PITA problem fixed. After checking every thing on the car but the tire pressure, I finally figured out the problem.

I wired in an intermittant switch in place of the fuel pump relay. I did this during one of the car's 'wont start' phases. By doing this, I validated that the fuel pump was actually getting power and SHOULD be producing pressure. Since it still did not produce more than 30lb of pressure, I decided that the Pump itself was the problem.

I went and got another pump ($125). Pulled out the tank and swapped pumps. I replaced the original harness this time, although nothing seems to be wrong with it.

I have driven it around all weekend and the problem seems to be fixed!

The wife seems to be happy!!!!!

[tethoma]

Do you have the CPI engine? If so, it sounds like the injector (1 X 6) needs to be replaced? It will set you back $350 bones.

[caveeagle]

Well, after swapping out the fuel pump, it seemed to run fine for a few months.
About 3 weeks ago, it started running a bit rough. Last Saturday, it really went south. Starting with VERY rough running, stalling and unable to rev above ~2k rmp.
I finally decided to take it to a local shop that seems to have a good reputation.

They called me back to recommend these repairs:
Replace the CPI fuel injection with the upgraded CMI system recommended by GM. They are also telling me that the fuel pump needs replacing, even though this pump is the one I just replaces 3 months ago!

Cost-~$1800

They also told me that there was a small oil leak from the manifold that would cost an additional $400 to fix if I wanted them to get that far into it.

This is a Van, to access is a real PITA.

The parts for this job should be arounf 5-600 clams at NAPA. Does that seem like a reasonable amount of labor for this?

This van has right at 130k mikes on it. The wife would like to keep it for another 2 years before upgrading.